Article
Chemistry, Physical
Mayur Khan, Sanjay K. Kedia, Ambuj Mishra, Devesh Kumar Avasthi, Ambuj Tripathi
Summary: The study investigates the improvement of crystallinity in few-layer MoS2 through thermal annealing and ion-beam induced annealing. It is found that annealing in Ar-gas environment at 300℃ results in high crystallinity, while higher annealing temperature decreases crystallinity and reduces MoS2 flake size. Ion-beam induced annealing shows improved crystallinity at lower ion fluence.
APPLIED SURFACE SCIENCE
(2023)
Article
Chemistry, Multidisciplinary
Hyunwoo Kim, Seunghyun Moon, Jongwoo Kim, Sang Hwan Nam, Dong Hwan Kim, Jeong Seop Lee, Kyoung-Ho Kim, Evan S. H. Kang, Kwang Jun Ahn, Taewan Kim, ChaeHo Shin, Yung Doug Suh
Summary: The study investigated photoluminescence enhancement from few-layer MoS2 transferred on Au nanostructure arrays with controlled localized surface plasmon resonance (LSPR) spectral positions. Two distinctive regimes in LSPR mode-dependent PL enhancement were revealed, with a maximum enhancement of around 40-fold at zero detuning and a modest enhancement of around 10-fold with red-shift detuned LSPR, attributed to LSPR-induced optical field enhancement and the Purcell effect, respectively.
Article
Materials Science, Multidisciplinary
Alois Arrighi, Elena del Corro, Daniel Navarro Urrios, Marius Vasile Costache, Juan F. Francisco Sierra, Kenji Watanabe, Takashi Taniguchi, Jose A. Garrido, Sergio O. Valenzuela, Clivia M. Sotomayor Torres, Marianna Sledzinska
Summary: State-of-the-art fabrication and characterisation techniques were used to measure the thermal conductivity of suspended, single-crystalline MoS2 and MoS2/hBN heterostructures. The results showed that the heterostructure exhibited a significantly increased thermal conductivity due to the high thermal interface conductance between MoS2 and hBN, as well as the efficient in-plane heat spreading driven by hBN.
Article
Multidisciplinary Sciences
Zhongtao Lin, Wuguo Liu, Shibing Tian, Ke Zhu, Yuan Huang, Yang Yang
Summary: By using Raman spectroscopy, the thermal expansion coefficients of suspended MoS2 and supported MoS2 were investigated, showing significant differences. Additionally, negative thermal expansion coefficients were observed in MoS2 below 175K, which is attributed to bending vibrations in the layer during cooling. This study demonstrates that Raman spectroscopy is a useful tool in exploring the thermal properties of few-layer MoS2 for potential application in photoelectronic devices.
SCIENTIFIC REPORTS
(2021)
Article
Chemistry, Physical
Wentao Hou, Yuan Sun, Yu Zhang, Tingting Wang, Liqian Wu, Youwei Du, Wei Zhong
Summary: A mixed-dimensional heterostructure of MoS2 deposited few-layer Ti3C2Tx nanosheets was synthesized to enhance the supercapacitor performance, delivering a remarkable specific capacitance and excellent cycling stability. The heterostructure shows high energy density and can serve as an archetype for enhancing electrochemical performance by integrating different materials' advantages synergistically.
JOURNAL OF ALLOYS AND COMPOUNDS
(2021)
Article
Nanoscience & Nanotechnology
Er-Xiong Ding, Peng Liu, Hoon Hahn Yoon, Faisal Ahmed, Mingde Du, Abde Mayeen Shafi, Naveed Mehmood, Esko I. Kauppinen, Zhipei Sun, Harri Lipsanen
Summary: Fabricating electronic and optoelectronic devices using a facile electrode fabrication process with SWCNT films leads to improved device performance. Dry-transferred SWCNT films as transparent electrodes in Schottky diodes for photodetector applications increase light absorption in photoactive MoS2 channels. The enhanced photodetection is attributed to FN tunneling and internal photoemission of charge carriers excited from indium tin oxide across the MoS2 layer.
ACS APPLIED MATERIALS & INTERFACES
(2023)
Article
Chemistry, Multidisciplinary
Yue Niu, Junwei Zeng, Xiangcheng Liu, Jialong Li, Quan Wang, Hao Li, Nicolaas Frans de Rooij, Yao Wang, Guofu Zhou
Summary: A photovoltaic self-powered NO2 gas sensor based on n-MoS2/p-GaSe heterojunction was successfully prepared, showing a significant response toward ppb-level NO2 with short recovery time and high selectivity at room temperature. This device has a low limit of detection (20 ppb) for NO2, making it one of the most sensitive self-powered room-temperature gas sensors reported to date.
Article
Thermodynamics
Zhao-Xia Qu, Jin-Wu Jiang
Summary: This study derives an analytic formula for the effect of bubbles on the length variation of the MoS2 layer in van der Waals layered structures. It is found that the nonlinear plate theory with the generalized van der Waals equation provides the most accurate description for the bubble effect. The analytic formula shows that bubbles can cause strong thermal contraction for few-layer MoS2 with increasing temperature, which is verified by molecular dynamic simulations.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2023)
Article
Chemistry, Multidisciplinary
Zhikang Wu, Feifei Li, Xiya Li, Yang Yang, Xiao Huang, Hai Li
Summary: This article introduces the improvement of optoelectronic application of graphene and GONS by wrapping ammonium tetrathiomolybdate into GONS and converting it into MoS2 nanosheets and RGO through thermal annealing. The as-prepared MoS2@RGONS shows a much better photoresponse than pure RGONS under visible light. Therefore, MoS2@RGONS is expected to be a promising material in the fields of optoelectronic devices and flexible electronics.
Article
Chemistry, Physical
Cen Zhang, A. Kun Liu, Yicen Zhang, Linchao Mu, Zhiwen Zhang, Jing Huang, Yanze Wang, Tao Yang, Jing Cao, Congshan Zhou
Summary: A dual strategy of layer and defect engineering was utilized to prepare few-layer and defect-rich MoS2 catalyst for the hydrodeoxygenation of phenol compounds to aromatics. The catalyst exhibited excellent performance with high conversion and selectivity, attributed to the structure of MoS2 and the formation of Co-Mo-S active phase.
APPLIED CATALYSIS A-GENERAL
(2021)
Article
Chemistry, Physical
Tingting Ren, Wenrou Tian, Qian Shen, Zhenting Yuan, Dongyun Chen, Najun Li, Jianmei Lu
Summary: This study demonstrates that MoS2 with different crystal phases exhibit distinct piezoelectric properties, with 1T/3R-MoS2 showing higher degradation efficiency due to its unique crystal structure and piezoelectric effects.
Article
Chemistry, Multidisciplinary
Xiaoyan Zhang, Shujia Yin, Lei Bao, Qianlong Wang, Jia Liang, Lidong Guo, Honglei Xue, Yujia Huang, Hongwei Zhu, Chunlei Wan, Wangyang Fu
Summary: The development of highly sensitive nanoelectronic biochemical sensors based on 2D materials has attracted great interest for applications in environmental monitoring and medical diagnosis. By connecting electrodes on a MoS2/CTAB superlattice, current conduction near the surface can be limited, allowing for quick prototyping of electrolyte-gated quasi-2D/organic superlattice transistors. The hybrid superlattice transistor shows exceptional sensing response to biomolecules, surpassing the Nernst limit, and achieves an outstanding limit of detection down to a 10-16 M concentration.
CELL REPORTS PHYSICAL SCIENCE
(2023)
Article
Chemistry, Multidisciplinary
Baoyu Wang, Jr-Hau He, Bin Yu, Xin He, Fei Xue
Summary: The dynamic optical responses to external strains of 2D-3D hybrid heterostructures are rarely studied. In this work, we demonstrate the strain-tuned recombination dynamics of monolayer-MoS2 and thin-film-GaN heterostructures. The optical excitons in the heterostructures can be modulated by strains due to the MoS2 piezoelectric dipoles across the interfaces. The photoluminescence intensity of the heterostructures shows quenched responses with the increase in tensile strains, and the change in photoluminescence spectra strongly depends on the directions of the applied strains.
Article
Chemistry, Physical
Jing Dong, Wenjian Fang, Hui Yuan, Weiwei Xia, Xianghua Zeng, Wenfeng Shangguan
Summary: The preparation of efficient noble-metal-free catalysts through MoS2/ZnCdS/ZnS dual heterostructures has led to high hydrogen production rates and stability in water-splitting reactions.
ACS APPLIED ENERGY MATERIALS
(2022)
Article
Engineering, Electrical & Electronic
Xing Su, Dongping Wu
Summary: In this study, a novel microwave annealing technique was proposed to enhance the performance of multilayer MoS2 FETs on flexible plastic substrates. By modulating the thickness of the electrode overlay, different annealing temperatures for different materials could be achieved, thereby improving annealing efficiency. Compared to traditional thermal annealing, this method showed superior performance in terms of improved electrical properties and reduced annealing time.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2023)
Correction
Physics, Applied
Jaesung Lee, Philip X. -L. Feng
APPLIED PHYSICS LETTERS
(2022)
Article
Physics, Applied
Xu-Qian Zheng, Hongping Zhao, Philip X. -L. Feng
Summary: Beta gallium oxide is an emerging semiconductor material with attractive properties for future electronics and sensors. This article provides an overview of the development of beta gallium oxide micro/nanomechanical systems and discusses their potential applications in power and RF electronics. The article also addresses challenges and proposes strategies for the future development of beta gallium oxide M/NEMS.
APPLIED PHYSICS LETTERS
(2022)
Article
Physics, Applied
Jaesung Lee, Matthew D. LaHaye, Philip X. -L. Feng
Summary: This study reports on the analysis and design of atomically thin graphene resonant nanoelectromechanical systems (NEMS) with anharmonicity in the quantum regime. The study provides design guidelines and scaling parameters for graphene NEMS with desired nonlinear dynamical characteristics. The results open possibilities for a new type of 2D resonant NEMS qubits.
APPLIED PHYSICS LETTERS
(2022)
Article
Engineering, Electrical & Electronic
Wen Sui, Xu-Qian Zheng, Ji-Tzuoh Lin, Jaesung Lee, Jim L. Davidson, Robert A. Reed, Ronald D. Schrimpf, Bruce W. Alphenaar, Michael L. Alles, Philip X-L Feng
Summary: GaN is an excellent material for MEMS due to its outstanding electrical and mechanical properties. This study investigates the effects of ion radiation-induced displacement damage on GaN/AlN resonant MEMS, revealing a significant decrease in resonance frequencies and visible deformation at high fluence due to changes in Young's modulus and built-in stress.
IEEE TRANSACTIONS ON NUCLEAR SCIENCE
(2022)
Article
Physics, Applied
Jaesung Lee, Steven W. Shaw, Philip X. -L. Feng
Summary: This study experimentally demonstrates giant parametric amplification and spectral linewidth narrowing in atomically thin NEMS resonators. These findings suggest rich opportunities for controlling oscillations in 2D NEMS through parametric and nonlinear effects, opening up possibilities for creating high-performance, thin resonators and oscillators for signal transduction and sensing.
APPLIED PHYSICS REVIEWS
(2022)
Article
Chemistry, Multidisciplinary
Wen Sui, Haoran Wang, Jaesung Lee, Afzaal Qamar, Mina Rais-Zadeh, Philip X. -L Feng
Summary: This study demonstrates the experimental performance of aluminum scandium nitride (AlScN)-on-cubic silicon carbide (SiC) heterostructure thin film micromachined resonant transducers at high temperatures up to 600 degrees C. The investigation of macroscopic and microscopic vibrations using ultrasensitive laser interferometry and Raman spectroscopy reveals the temperature coefficients of resonance frequency and the potential applications of higher-order modes as high-temperature-tolerant sensors or detectors. The correlation between the phonon modes and temperature variation suggests the role of residual strain in mediating the vibrations in the crystal lattice and the diaphragm.
ADVANCED FUNCTIONAL MATERIALS
(2022)
Article
Chemistry, Multidisciplinary
Rui Yang, S. M. Enamul Hoque Yousuf, Jaesung Lee, Pengcheng Zhang, Zuheng Liu, Philip X. -L. Feng
Summary: This study experimentally demonstrates dynamical phonon softening in atomically thin molybdenum disulfide (MoS2) NEMS resonators by directly coupling Raman spectroscopy with optical interferometry resonance motion detection. High-amplitude nonlinear resonances can enhance the Raman signal amplitude and introduce Raman modes softening up to 0.8 cm(-1).
Article
Engineering, Electrical & Electronic
Pablo Guzman, Toan Dinh, Afzaal Qamar, Jaesung Lee, X. Q. Zheng, Philip Feng, Mina Rais-Zadeh, Hoang-Phuong Phan, Thanh Nguyen, Abu Riduan Md Foisal, Huaizhong Li, Nam-Trung Nguyen, Dzung Viet Dao
Summary: This paper introduces a new concept of bi-layered monolithic silicon carbide resonators that utilize thermal-piezoresistive pumping to boost the quality factor. The device operates through electrothermal actuation and the structural stress modulates the electrothermal force via the piezoresistive effect. The unique design of the double SiC layer allows energy to be pumped into the system, resulting in an enhancement of the effective quality factor.
SENSORS AND ACTUATORS A-PHYSICAL
(2022)
Article
Engineering, Electrical & Electronic
Jaesung Lee, Michael W. McCurdy, Robert A. Reed, Ronald D. Schrimpf, Michael A. Alles, Philip X. -L. Feng
Summary: We report on the in situ measurement of proton radiation effects on single-crystal silicon comb-drive resonant MEMS devices. The resonators exhibit highly sensitive responses in resonance characteristics while maintaining robust operations. Based on the TRIM simulations, the observed radiation effects on resonance frequency could be attributed to a combination of ionizing and displacement damage effects. These in situ observations of radiation effects on comb-drive MEMS resonators show the promising potential of dynamic MEMS for new types of radiation sensors or radiation-hardened signal processing components.
IEEE TRANSACTIONS ON NUCLEAR SCIENCE
(2023)
Article
Chemistry, Multidisciplinary
Fan Ye, Arnob Islam, Yanan Wang, Jing Guo, Philip X. -L. Feng
Summary: This work presents experimental demonstrations of reversible crystalline phase transition in ultrathin molybdenum ditelluride (MoTe2) controlled by thermal and mechanical mechanisms on the van der Waals (vdW) nanoelectromechanical systems platform. The phase transition is triggered by rising temperature and strain level, and can be monitored in situ using Raman spectroscopy. The results not only deepen the understanding of MoTe2 phase transition, but also demonstrate a novel platform for engineering MoTe2 phase transition and multiphysical devices.
Article
Chemistry, Multidisciplinary
Fan Ye, Qingchang Liu, Baoxing Xu, Philip X. -L. Feng, Xian Zhang
Summary: Heat dissipation is a major problem in high-performance electronics, especially in emerging nanoelectronic devices. This study reports ultra-high interfacial thermal conductance in encapsulated van der Waals heterostructures, which can significantly enhance thermal transport. The experimental results show that the interfacial thermal conductance between the transition metal dichalcogenides MX2 and hexagonal boron nitride (hBN) reaches 74 +/- 25 MW m(-2) K-1, at least ten times higher than non-encapsulation structures. Molecular dynamics calculations reveal that the full encapsulation by hBN layers is responsible for the high interfacial conductance. This study uncovers new thermal transport mechanisms and provides insights for building hBN-encapsulated nanoelectronic devices with improved thermal management.
Article
Acoustics
Tahmid Kaisar, S. M. Enamul Hoque Yousuf, Jaesung Lee, Afzaal Qamar, Mina Rais-Zadeh, Soumyajit Mandal, Philip X. -L. Feng
Summary: We report the first experimental demonstration of five self-sustaining feedback oscillators referenced to a single multimode resonator using piezo-electric aluminum nitride on silicon (AlN/Si) microelectro- mechanical systems (MEMS) technology. The integrated piezoelectric transduction enables efficient readout of five resonance modes of the same AlN/Si MEMS resonator, and their mode-dependent phase noise and frequency stability are measured and analyzed. The overall promising performance of the five oscillators suggests suitability for multimode resonant sensing and real-time frequency tracking.
IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL
(2023)
Proceedings Paper
Engineering, Electrical & Electronic
Tahmid Kaisar, S. M. Enamul Hoque Yousuf, Jaesung Lee, Afzaal Qamar, Mina Rais-Zadeh, Soumyajit Mandal, Philip X. -L. Feng
Summary: This study reports the first experimental demonstration of multiple self-sustaining feedback oscillators referenced to a single multimode resonator. The use of piezoelectric aluminum nitride on silicon (AlN/Si) microelectromechanical systems (MEMS) technology enables efficient readout of multiple resonance modes of the same AlN/Si MEMS resonator. The oscillators exhibit low phase noise and excellent frequency stability, making them suitable for clock, timing, sensing, and tracking applications.
2022 INTERNATIONAL ELECTRON DEVICES MEETING, IEDM
(2022)
Proceedings Paper
Engineering, Electrical & Electronic
Jaesung Lee, Steven W. Shaw, Philip X-L Feng
Summary: This study demonstrates the experimental generation of a phononic frequency comb in atomically thin MoS2 resonant NEMS. The spacing of the comb teeth can be tuned by voltage and driving, showing strong tunability.
2022 IEEE 35TH INTERNATIONAL CONFERENCE ON MICRO ELECTRO MECHANICAL SYSTEMS CONFERENCE (MEMS)
(2022)
Proceedings Paper
Engineering, Electrical & Electronic
S. M. Enamul Hoque Yousuf, Yuncong Liu, Xu-Qian Zheng, Afzaal Qamar, Mina Rais-Zadeh, Philip X-L Feng
Summary: This paper reports on an experimental study of actuation techniques for AlN/Si heterostructure resonant MEMS and compares their quality factors and energy losses. A new scheme with non-contact overhanging electrode inducing gradient forces is developed to electrically drive the devices. The electrical drive enables the detection of unseen resonant modes and results in lower energy dissipation compared to the optical drive.
2022 IEEE 35TH INTERNATIONAL CONFERENCE ON MICRO ELECTRO MECHANICAL SYSTEMS CONFERENCE (MEMS)
(2022)